Heretofore, in general, in order to make plastic moldings have scratch resistance, a method of providing a coating film with scratch resistance on the surface of the molding has been employed. Coating compositions proposed to be used for forming such a coating film, include, for example, a coating composition containing a colloidally-dispersed silica sol (Japanese Patent Laid-Open No. 111336/1978), a coating composition containing fine tin oxide particles coated with fine tungsten oxide particles (Japanese Patent Laid-Open No. 172369/1991), a coating composition containing a sol of tin oxide colloid particles modified with tin oxide-tungsten composite colloid particles (Japanese Patent Laid-Open No. 25603/1994), etc.
However, these prior coating compositions are all problematic in that, when they are coated, for example, on optical substrates, they could not form film coatings capable of making the coated substrates have good scratch resistance and good moisture resistance while also having an esthetic appearance (as used herein, esthetic appearance means that the coated substrates do not form interference fringes caused by a difference in the refractive index between the film coating and the substrate) and good weather resistance. Furthermore, even if an additional deposited film were provided thereon, the resulting coated substrates still could not have satisfactory scratch resistance and satisfactory moisture resistance while also having an esthetic appearance and good weather resistance.
The object of the present invention is therefore to solve the problems with the prior film coatings. Specifically, it is an object to provide an optical element having a cured film, which has good esthetic appearance, good weather resistance, good scratch resistance and good moisture resistance, and whose properties are little degraded even when further coated with a deposited film.